As for those plot holes mentioned at the beginning:
Why is it that C-3PO is made on Tatooine but doesn't know where he is in ANH?
Simple: C3PO is an idiot. :-)
And how come Uncle Owen doesnt recognize C-3PO or R2-D2 when the Jawas sell them to him?
Couple of possibilities here: Maybe he did recognise them, but didn't want to say anything as Luke would have started asking awkward questions? Or maybe he just assumed logically that they were totally different droids, remember there could be thousands that look like them. In either case, he obviously realises later when Luke mentions Obi Wan, so decides to get the memories erased. ( I just noticed you mentioned about droids looking alike, so maybe the first theory is better)
Why doesnt Vader look for Obi-wan and his son on Tatooine or on the Lar's farm before/or during ANH?
I don't think he knows about Luke or Leia at that point. As for ObiWan, maybe he thinks he is dead? ("Surely he must be dead by now")I have often wondered if Vader realises he has sent his troops to murder his own step brother...
Now, for Jimbos plot holes:
One the actress who plays Beru in Attack of the Clones has brown eyes the actress who plays were in A New Hope has blue eyes.
Who cares? Maybe she is wearing contact lenses. Maybe she is a humanoid species whos eyes change color as they get older. Maybe her eyes were replaced with artificial ones. Or maybe the people who cast her didn't think anyone would notice...
In A New Hope, The Empire Strikes Back, the Clone Wars cartoons, and Attack of the Clones the clones are shown as very efficient warriors but in Return of the Jedi they can't kill more then a few ewoks.
See above re the clone thing... another explanation may be that the stormtroopers were out of practice as they never had to fight any real battles any more... they weren't expecting any resistance... but actually I do agree to a point, especially since they are supposed to be Palpatines "best troops". One thing that irks me is when Chewbacca commandeers that walker. I mean, if you were in a tank and someone climbed on top of it, would you just open the hatch and let them in? Sheesh.
Why would the Empire build another Death Star after how easily the last was destroyed?
Luke summed that one up nicely: "YOur overconfidence is you weakness". The Emperor believed he was prepared this time; he had forseen the destruction of the rebels, he had fed them misinformation, and he was to arrogant to believe anyone could defeat him.
Padme tells a clone after she falls out of the ship "we got to get to that hanger" how did she know about the hanger?
I'd have to watch that bit again to be sure, but I imagine someone mentioned that Dooku was headed for his ship before she fell out. Could be wrong though.
In the Clone Wars cartoons Mace wipes out droids without his lightsaber he couldn't fight this well in Attack of the Clones
Meh... it's a cartoon. Who cares (obviously I don't).
In The Phantom Menace when Darth Maul appears in front of them why doesn't Padme order her men to fire. Even he could not block that many shots. Instead the Jedi handle it resulting in Qui-Gons death.
I have only watched that "film" once so can't comment. If you want to talk about plot problems in that film how about: A child "accidently" defeating an entire blockade single handedly; Or a group of supposedly incredibly wise Jedi relying on an idiot who speaks and acts like a two year old to save a planet; Or the most obvious mistake of all, that this "film" was ever made and released at all...
In The Phantom Menace when the Jedi coucil arrives on Naboo a bald black man comes out who is suppose to be Mace Windu but is clearly not Samual L Jackson.
Dunno; See above.